Double-Oriented Electrical Steel Sheet for Transverse Magnetism

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Solution Overview

Problem

Conventional electrical steel sheets exhibit excellent magnetism only in the rolling direction and poor magnetism in the transverse direction, limiting their application in transformers and generators, particularly those with slow rotation speeds like wind power generators, where magnetic flux density and DC magnetic characteristics are crucial.

Innovation Solution

A double-oriented electrical steel sheet is developed with a specific alloy composition and manufacturing process, including controlled ratios of Mn and S, forsterite layers, and insulating layers, to achieve excellent magnetism in both the rolling and transverse directions, enhancing magnetic flux density and permeability across various frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cross-rolling method is used to achieve cube orientation, then magnetism in transverse direction is improved, but productivity deteriorates

Engineering Contradiction:
Improvemagnetism in transverse directionVSAvoidcontinuous production capability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Instead of using cross-rolling process changes, the patent achieves the desired cube orientation by controlling the final rolling reduction ratio (80-95%) and performing controlled recrystallization annealing. This maintains continuous production capability while achieving the required {100}<uvw> texture with 30°≤γ≤60° for excellent transverse direction magnetism.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If alloy amount is reduced to increase Fe fraction, then magnetic flux density is improved, but manufacturing precision deteriorates

Engineering Contradiction:
Improvemagnetic flux densityVSAvoidtexture control precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent maintains a balanced alloy composition (0.003-0.03% C, 0.005-0.05% Si, 0.01-0.1% Mn, 0.001-0.01% Ti) rather than reducing alloy content. The key parameter change is in the controlled recrystallization annealing process (800-1000°C for 5-30 minutes) which achieves precise texture control to {100}<uvw> orientation, enabling both high magnetic flux density and excellent texture precision.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides a significant improvement in magnetic flux density and permeability in both directions, enabling more efficient energy generation and reduced energy loss in generators, particularly suitable for wind power applications.

Implementation Method 1

performing secondary recrystallization annealing on the cold-rolled steel sheet

Methodology Applied
Scientific EffectRecrystallization annealing: Annealing

Implementation Method 2

excellent magnetism in a rolling direction and a transverse direction by appropriately controlling a ratio of Mn and S

Methodology Applied
Scientific EffectMagnetic flux density: Magnetism

Data Source

PatentUS11802319B2Double oriented electrical steel sheet and method for manufacturing same
Publication Date: 2023.10.31 POHANG IRON & STEEL CO LTD

AI summary

A double oriented electrical steel sheet includes: 2.0 to 6.0% of Si, 0.0005 to 0.04% of Al, 0.0001 to 0.003% of S, 0.02 to 1.0% of Mn, equal to or less than 0.003% of N, excluding 0%, equal to or less than 0.01% of C, excluding 0%, equal to or less than 0.01% of Ti excluding 0%, 0.005 to 0.10% of P as wt %, and a remainder including Fe and inevitable impurities. Such a double oriented electrical steel sheet satisfies Formula 1:[Mn]/[S]≥60,  [Formula 1]where, [Mn] and [S] are contents (wt %) of Mn and S, respectively.